WO2013080158A1

WO2013080158A1 - Headlight for automotive lighting applications

Info

Publication number: WO2013080158A1
Application number: PCT/IB2012/056834
Authority: WO
Inventors: Nils Benter; Benno Spinger; Michael BEIFUSS
Original assignee: Koninklijke Philips Electronics N.V.; Philips Intellectual Property & Standards Gmbh
Priority date: 2011-12-02
Filing date: 2012-11-29
Publication date: 2013-06-06

Abstract

The present invention relates to a headlight for automotive lighting applications, at least comprising a central light source (2) mounted on a base (1), an outcoupling optics (5) arranged in front of the central light source (2), several LED light sources (3) and one or several optical elements (4) arranged between the LED light sources (3) and the out- coupling optics (5). The optical elements (4) are designed to guide and/or form light beams emitted from the LED light sources (3) such that the outcoupling optics (5) creates a light distribution of these light beams different from the light distribution of the light beam of the central light source (2). The proposed headlight allows the combination of a low beam (LB) function with a day time running light (DRL) using the same outcoupling optics without the need of any movable optical components.

Description

HEADLIGHT FOR AUTOMOTIVE LIGHTING APPLICATIONS

FIELD OF THE INVENTION

The present invention relates to a headlight for automotive lighting applications which at least comprises a central light source mounted on a base, an outcoupling optics arranged in front of the central light source and several LED light sources.

BACKGROUND OF THE INVENTION

Due to the increasing competition in the automotive market the styling of cars is an important measure to increase the attractiveness of the product. This also includes the styling of the headlight of the cars using an appropriate distribution of LED light sources. In particular, a combination of day time running light (DRL) with some other light functions which are used during night time will be interesting, because this offers the same styling during day and night increasing the recognition of the car.

In known automotive lighting systems the position light is combined with the DRL because this is easily managed by dimming of the light sources. A combination of the low beam (LB) light with the DRL is desirable but challenging. The two functions of LB lighting and DRL should not only fulfill the legally required intensity values but especially the DRL also have to create a homogeneous appearance of the lamp itself. The required LB light distribution and the DRL beam distribution are completely different as is indicated schematically in figure 1. Figure la shows an example of the light distribution of a LB light, figure lb the light distribution of a DRL in a very schematic representation. The different regions 7 separated by lines schematically indicate different light intensities decreasing with increasing distance from the shaded region 6 with the highest light intensity. The LB light requires an asymmetric light distribution, whereas the DRL shows a completely symmetric homogenous distribution. A combination of both lighting functions in the same headlight creating the two different beam distributions is therefore very difficult.

In order to achieve both automotive functions with the same headlight US 2009/0251915 Al proposes to provide only a central light source, the light distribution of which is changed by moving a single lens or lens portion within the light beam path or into the light beam path to alter the divergence of the light beam. With this measure, the same outcoupling optics can be used for the LB mode and the DRL mode. This solution, however, requires a mechanical movement of optical elements which increases the sensitivity of the headlight for failures.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a headlight for automotive lighting applications which allows the combination of a day time running light (DRL) with a low beam (LB) light using the same outcoupling optics without the need of mechanically movable optical components. The headlight should be able to provide a homogeneous appearance in the DRL mode and a high optical efficiency.

The object is achieved with the headlight for automotive lighting applications according to claim 1. Advantageous embodiments of the headlight are subject matter of the dependent claims or are disclosed in the subsequent portions of the descriptions and preferred embodiments.

The proposed headlight at least comprises a central light source mounted on a base, an outcoupling optics arranged in front of the central light source and designed to create a first light distribution of a first light beam emitted from the central light source, one or several LED light sources and one or several optical elements arranged in the beam path between the LED light sources and the outcoupling optics. The LED light sources may be mounted on the same base as the central light source or on an additional base connected to the base of the central light source. The optical elements are designed to guide and/or form second light beams emitted from the LED light sources such that the outcoupling optics creates a second light distribution of the second light beams different from the first light distribution. The optical elements, in the following also called micro-optical elements due to their small size, are mounted statically relative to the LED light sources and the base.

With this construction of the headlight the same outcoupling optics is used for the generation of the first light distribution and for the generation of the second light distribution without mechanically moving any components of the headlight. This allows a design of the headlight for performing an automotive LB lighting function with the first light distribution and a DRL function with the second light distribution. The central light source and the outcoupling optics are arranged and designed in such an embodiment to perform the automo- tive LB lighting function. At the same time the LED light sources and the micro-optical elements are arranged and designed to perform in combination with this outcoupling optics the automotive DRL function. The central light source and the outcoupling optics may also be arranged and designed to perform a high beam and/or front fog lighting function. Alternatively or additionally the LED light sources or some of these light sources may be arranged and designed together with the corresponding micro-optical elements to perform a front turn indicator function and/or a position light function. Due to the use of the one or several micro- optical elements most of the light emitted by the LED light sources are directed through the outcoupling optics resulting in a good optical efficiency which decreases the amount of the required LED light sources and therefore decreases the costs.

The proposed construction allows to mount a central light source having a higher mounting height than the LED light sources together with the LED light sources on the same base and to achieve nevertheless a light emission of both types of light sources at the same level with respect to the outcoupling lens. To this end the micro-optical elements are designed to have their outcoupling faces at the same level as the emission surface of the central light source. This avoids to mount the LED light sources in another level as the central light source asking for a much more complicated board layout and manufacturing process. The term mounting height in this context means the distance of the most distant edge of the corresponding element from the base. The LED light sources and the micro-optical elements are thus preferably arranged and designed such the combination of each LED light source with its corresponding micro-optical element has approximately the same mounting height on the base or relative to the base as the central light source. With approximately the same height is meant that the height of the combination of LED light sources and micro- optical elements on the base does not deviate more than 10% from the height of the central light source on the base.

In an embodiment of the proposed headlight the LED light sources are arranged to at least partly surround the central light source on the base. The micro-optical elements then preferably form a continuous or interrupted frame at least partly surrounding the central light source, i.e. are made of one single element or of several separated elements sur- rounding the central light source. The micro-optical elements may be designed to optically is smear out dark gaps between the LED light sources and/or between the LED light sources and the central light source. This leads to a homogeneous light distribution with a high optical efficiency compared to an arrangement without such micro-optical elements.

The base preferably comprises one or several electronic circuits for operating the central light source and the LED light sources. The base may also only include the electrical connections to the driving electronics for the light sources. This driving electronics, however, may also be integrated in the base. The proposed headlight can be applied in automotive lighting functions to combine two or more functions in one optical cavity, e.g. LB with DRL and/or the front turn indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described herein after. In the drawings:

Fig. 1 shows examples of a LB light and a DRL distribution;

Fig. 2 shows a schematic view of a cross section of the basic optical setup of the proposed headlight;

Fig. 3 shows a top view of an example of the micro-optical frame;

Fig. 4 shows a side view of an example of the micro-optical frame; and Fig. 5 shows a front cut view of an example of the micro-optical frame of the proposed headlight.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows an example for the different light distributions of a LB light (Fig. la) and a DRL (Fig. lb). The figure has already being described in the introductory portion of the present description. In order to achieve both light distributions commonly using the outcoupling lens and without any movable optical components, the headlight according to the present invention is provided.

Figure 2 shows a schematic cross sectional view of an example of such a headlight. In this example, the central LB light source 2 and several LED light sources 3 are mounted on a common printed circuit board 1 (PCB). The LB light source 2 is a high intensity light source, e. g. a LUXEON Altilon Core. This light source is positioned in the optical center of an optical outcoupling system, e. g. a lens or lens array or a reflector, which creates the whole or part of the required LB distribution. Figure 2 shows the corresponding outcoupling optics as an outcoupling lens 5. The LED light sources 3 are arranged on the PCB 3 to surround the LB light source 2. The central LB light source 2 is also surrounded by an optical element 4 (micro optic frame) which guides the light of the LED light sources 3 to the emission plane of the LB light source 2. The LED light sources 3 may be formed, e. g. by LUX- EON Altilon Fl LEDs. Due to the arrangement of the optical element 4 in front of the LED light sources 3, the light of the LED light sources 3 leaves the outcoupling face of the optical element 4 in the same plane as the emission plane of the LB light source 2 as shown in fig- ure 2. The optical element 4 is designed to smear out the dark gap between the LED light sources 3 as well as the gap between the LB light source 2 and the LED light sources 3. This increases the homogeneity of the beam distribution and the optical appearance.

Figure 3 shows a top view of an example of the LED light sources 3, the LB light source 2 and the optical element 4 which is formed of three separate parts in the present example. These three parts form an interrupted optical frame partly surrounding the LB light source 2, but may also be combined to one single element if desired. The LB light source 2 is connected via two wires to a driver electronics as also schematically indicated in the figure. The micro-optical element 4 are designed as a light guide for the light emitted by the LED light sources 3 in this example. As can be seen from figure 4, which shows a side view of the optical element 4, the height of the combination of optical frame and LED light sources on the PCB 1 is in the same order as the height of the LB light source on the PCB 1. The same arrangement is also shown in a front cut view in figure 5.

The micro-optical element or frame 4 may e. g. be stacked, glued or screwed on the PCB 1 or on a potential back side heat sink. For an integration of a front turn indicator function, additional amber light sources are positioned between the LED light sources 3 such that also the amber light is guided by the micro-optical elements 4.

While the invention has been illustrated and described in detail in the drawings and forgoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. The invention is not limited to the combination of LB and DRL and/or front turn indicator. Also other lighting functions may be realized, for example an additional high beam light function. The optical element is not restricted to a light guide but may also include other optical functions alternatively or in addition like the function of a lens. In the claims, the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims. LIST OF REFERENCE SIGNS printed circuit board

LB light source

LED light source optical element outcoupling lens region of highest intensity regions

Claims

1. Headlight for automotive lighting applications, at least comprising

- a central light source (2) mounted on a base (1),

- an outcoupling optics (5) arranged in front of the central light source (2) and designed to create a first light distribution of a first light beam emitted from the central light source (2),

- one or several LED light sources (3) and

- one or several optical elements (4) arranged between the LED light sources (3) and the out- coupling optics (5), said optical elements (4) being designed to guide and/or form second light beams emitted from the LED light sources (3) such that the outcoupling optics (5) creates a second light distribution of the second light beams different from the first light distribution.

2. Headlight according to claim 1,

wherein the central light source (2) and the outcoupling optics (5) are arranged and designed to perform an automotive low beam and/or high beam and/or front fog lighting function.

3. Headlight according to claim 1 or 2,

wherein the LED light sources (3) and the optical elements (4) are arranged and designed to perform in combination with the outcoupling optics (5) an automotive day time running light function and/or position light function and/or a front turn indicator function.

4. Headlight according to claim 1 or 2,

wherein the LED light sources (3) and the optical elements (4) are arranged and designed such that the combination of each LED light source (3) with the corresponding optical ele- ment (4) has approximately the same height on the base (1) or relative to the base (1) as the central light source (2).

5. Headlight according to claim 1,

wherein the LED light sources (3) are arranged to at least partly surround the central light source (2).

6. Headlight according to claim 5,

wherein said optical elements (4) form a continuous or interrupted optical frame at least partly surrounding (4) the central light source (2).

7. Headlight according to claim 5 or 6,

wherein said optical elements (4) are designed to optically smear out dark gaps between the LED light sources (3) and/or between the LED light sources (3) and the central light source (2).

8. Headlight according to claim 1,

wherein the base (1) comprises one or several electronic circuits for operating the central light source (2) and the LED light sources (3).

9. Headlight according to of claim 8,

wherein the base (1) is formed of a printed circuit board.

10. Headlight according to claim 1,

wherein the light sources (3) are mounted on the base (1) on which the central light source (2) is mounted, or on an additional base which is connected to the base (1) on which the central light source (2) is mounted.

11. Headlight according to claim 1 ,

wherein said optical elements (4) are light guides.